void fp (
    in      float2      coord   : TEXCOORD0,
    uniform samplerRECT data    : TEXUNIT0,
    out     float4      output  : COLOR
) {
    float4 x = texRECT(data,coord);
    float depth = 1;
    output.r = depth - x.r;
    output.g = depth - x.g;
    output.b = depth - x.b;
    output.a = depth;
}
